Throttle valve positioning device

ABSTRACT

The invention relates to a throttle valve positioning device, comprising a housing ( 12 ) with a bearing for a throttle valve shaft ( 20 ) and a throttle valve support ( 26 ), within which a throttle valve ( 24 ) pivots which sits on the throttle valve shaft ( 20 ), running into a shaft passage ( 44 ) in the support ( 26 ). According to the invention, air leakage may be avoided, whereby the periphery ( 34 ) of the throttle valve ( 24 ) is arranged at a separation from a passage ( 44 ) for the throttle valve shaft ( 20 ) in the throttle valve support ( 26 ).

The invention relates to a throttle valve positioning device having ahousing which forms a bearing arrangement for a throttle valve shaft andcomprises a throttle body in which a throttle valve is pivotable, saidthrottle valve sitting on the throttle valve shaft, which leads throughthe shaft passage into the throttle body, the housing being of one-pieceor split design.

In the hitherto known arrangements of throttle valves in the throttlebody which sit centrally on the throttle valve shaft or in a slot in thethrottle valve shaft, leakage air usually cannot be prevented fromflowing past in the region between throttle valve shaft, throttle valveand throttle housing and also via the shaft apertures in the bearings.The avoidance of leakage air is made more difficult in particular insplit housings having two housing shells, since the parting line of thetwo housing halves likewise lies in the region of the throttle valve, sothat, on account of the very high vacuum produced in the region of thethrottle valve, leakage air is drawn in in this region, which canscarcely be sealed off completely.

It has been attempted hitherto to reduce this problem by minimizing theshaft apertures and the mismatch in mold between the housing halves, itnot being possible in this way to absolutely remove the problem, butrather it only being possible to provide for a certain improvement withregard to leakage air at increased production costs.

The object of the present invention consists in providing a throttlevalve positioning device in which leakage air is minimized.

According to the invention, the object is achieved in that, in athrottle valve positioning device of the type mentioned at thebeginning, the circumference of the throttle valve, at least on oneside, lies next to the throttle valve shaft at a distance from itspassage in the throttle body.

The displacement of the throttle valve margin away from the shaftpassage and possibly also from the parting line of a split housingallows the leakage air to be minimized, since a sound seal between thecircumference, preferably provided with a sealing ring, of the throttlevalve and the inside of the throttle body, it being possible for theinside to be formed without joints away from the shaft passage and ahousing parting line. The displacement may be achieved, for example, bya throttle valve attached with lateral offset to the throttle valveshaft, or preferably by the throttle valve lying at an acute angle tothe throttle valve shaft, i.e. the throttle valve shaft passes throughthe throttle valve centrally at an acute angle. An elastic sealing ring,which preferably has certain radial mobility in a circumferentialgroove, can ensure that the deviations caused by the offset and/or theinclination of the throttle valve are compensated for.

In particular with the last-mentioned possibility, a design whichexhibits very little leakage air is possible, in particular if thethrottle valve circumference, at least on the side of the throttle valveshaft passage, lies on the suction side in the throttle body. In thisdesign, the passage especially critical for the sealing is arrangedtoward the drive in a region which lies in front of the throttle valveso that the shaft passage is screened off from the vacuum occurring onthe suction side. If, for example, the housing at the same time servesto accommodate an actuator and possibly gearing connected in between,the bottom shell can be designed as a closed-off, airtight unit, andvacuum is on no account applied to the gearbox. This in turn simplifiesthe sealing of the two housing halves, since the flange length in suchpositioning devices is relatively large.

With an inclined design of the throttle valve, in the embodimentdescribed above, the shaft bearing arranged opposite the shaft passagelies in the region of the vacuum, a factor which, however, is relativelyeasy to cope with on this side of the positioning device. Especiallypreferred is an embodiment in which the throttle valve shaft is mountedat this point in a closed bearing boss, for example directly in thethermoset of the throttle body material.

To avoid passage of air between throttle valve and throttle valve shaftin the case of a throttle valve inclined relative to the shaft, measuresfor sealing in this region are expedient. The throttle valve itself mayconsist of a thermoset or of a thermoplastic, for example filled PET orfilled PPS. The throttle valve may be integrally molded on a sleevewhich is made of metal or plastic and which completely or partlyencloses the shaft and can be secured to the latter in the case of asleeve made of plastic, said sleeve may in turn also be integrallymolded on the throttle valve shaft in one piece with the throttle valve,whereas in the case of metallic sleeves, said sleeves are preferablyscrewed to the throttle valve shaft or are welded to the latter.

Exemplary embodiments of the invention are dealt with in more detailbelow with reference to the attached drawings, in which:

FIG. 1 shows an oblique view of a throttle valve positioning device,with top housing half removed;

FIG. 2 shows a sectional illustration of the throttle valve positioningdevice according to FIG. 1, with housing top part;

FIG. 3 shows a view of a further embodiment of a throttle valvepositioning device, with lifted housing top part.

Shown in FIG. 1 is a throttle valve positioning device 10 whichessentially comprises a housing 12 with a bottom housing half 14 and atop housing half 16, an actuator 18, a throttle valve shaft 20, which iscoupled to the actuator 18 via gearing 22, and a throttle valve 24 whichsits on the throttle valve shaft 20 and is pivotable in a throttle body26 formed by the two housing halves 14, 16. In addition to a receptaclefor the actuator 18 and the gearing 22, the housing also forms a bearingarrangement for the throttle valve shaft 20 at a first, drive-sidebearing 28 in the parting line 30 between the two housing halves 14, 16and at a second bearing 32 on the side opposite the drive in thethrottle body 26. The second bearing 32 is at a distance from theparting line 30 between the housing halves and may also be designed as aclosed bearing boss, whereas in FIG. 2 the bearing 32 is shown openoutward.

The actuator 18 and the gearing 22 and also those regions of the twohousing halves 14, 16 which enclose them are designed in a manner knownper se and are therefore slot to be discussed in more detail here.

In deviation from conventional solutions, the throttle valve 24 does notsit centrally on the throttle valve shaft or in a split throttle valveshaft, but rather is designed to be offset relative to the throttlevalve shaft in such a way that the circumference 34 of the throttlevalve 24 bears next to the throttle valve shaft 20 on the inside againstthe throttle body 26. To this end, in the exemplary embodiment shown,the throttle valve 24 is arranged inclined relative to the throttlevalve shaft 20, an angular range of between 5° and 25° being expedient.In the contact region of the circumference 34 of the throttle valve 24,the throttle body 26 is formed with a correspondingly inclined region36, the walls of which lie perpendicularly to the plane defined by thethrottle valve 24 in its completely closed position. The adaptation ofthe wall of the throttle body to the inclination of the throttle valverelative to the throttle valve shaft reduces the actuating forces andavoids jamming in the closed position.

In the exemplary embodiment shown in FIGS. 1 and 2, the inclined region36 is formed essentially by the bottom housing half 14, i.e., in theclosed position of the throttle valve, the inclined region 36, whichtogether with the throttle valve provides for the sealing, is designedwithout joints. This provides for an excellent sealing effect, so thatthe leakage air is reduced to a minimum.

The throttle valve 24 is connected to the shaft in a rotationally fixedmanner by means of a sleeve 38, it being possible for the throttle valveto be integrally molded with the sleeve directly on the throttle valveshaft 20, which is made of steel, or for it to be secured to the shaftvia a metal insert which is welded or screwed to the shaft. In thesolution with a metal insert, the throttle valve can again be integrallymolded on said metal insert. Suitable materials for the body of thethrottle valve are thermosetting plastic or thermoplastic, such as, foren-ample, filled PEI (polyether imide) or filled PPS (polyphenylenesulfide).

To improve the sealing between throttle valve and throttle body 26, apiston ring or sealing ring 40, which can be made of an elastic plastic,for example PEEK (polyaryletherketone, polyetheretherketone) with PTFEfilling or pure PTFE, is embedded in the circumference 34 of thethrottle valve 24. This piston ring 40 is held in a circumferentialgroove 42, which is designed to be so deep that the piston ring 40 canbe pressed in elastically in the radial direction. The radial mobilityof the elastic piston ring 40 and its inherent elasticity ensure thatthe deviations of the path of movement, which are caused by theinclination of the throttle valve, during the pivoting of the throttlevalve are compensated for, so that an optimum sealing effect cannonetheless be achieved. Furthermore, the piston ring 40 is suitable forcompensating for production tolerances, so that the latter likewisecannot be the cause of leakage air.

Due to the special arrangement of the throttle valve 24 in the throttlevalve positioning device 10 shown in FIGS. 1 and 2, the passage 44 ofthe throttle valve shaft 20 into the throttle body 26 is relieved ofvacuum, since the vacuum side, in accordance with the illustration, lieson the fresh-air side below the throttle valve 24 and the throttle valveshaft. This means that, in particular the case of a closed design of thesecond bearing 32, especially sound sealing against leakage air isachieved, since vacuum cannot be applied to the closed housing 12 viathe passage location 44. As a result, the sealing of the two housinghalves 14, 16 relative to one another is simplified,

The two housing halves 14, 16 may be produced from plastic, inparticular a thermoset, which is also suitable for directly forming thebearing 32, so that the throttle valve shaft, during assembly, merelyneeds to be inserted there into the closed bearing boss.

In the embodiment of a throttle valve positioning device 110 shown inFIG. 3, in which the drive and that region of a housing 112 whichsurrounds said drive have been omitted, a parting line 130 between thetwo housing halves 114, 116 runs both through the first drive-sidebearing 128 of the throttle valve shaft 120 and through the oppositesecond bearing 132, i.e. the parting line 130 lies essentially in theplane defined by the position of the throttle valve shaft 120. Only inthe region of the throttle body 126 is the parting line 130 designed soas to be inclined in accordance with the inclined region 136, with aslope corresponding to the throttle valve inclination. This makes itnecessary for a wall section 150 formed parallel to the flow directionin the throttle body 126 to be provided between the region of the tophousing half 116, this region forming part of the throttle body 126, andthe remaining housing region, so that two parting lines are produced inthe contact region of the sealing ring 140 at the circumference 134 ofthe throttle valve 120. However, these parting lines are not criticalfor the sealing on account of their essentially perpendicular courserelative to the direction of movement of the sealing ring in this regionduring the positioning of the throttle valve. The advantage of theembodiment shown in FIG. 3 consists in the simpler assembly, since theunit of drive, gearing, throttle valve shaft and throttle valve, whenhousing halves 114, 116 are separated, can be inserted into its bearingsin a simple manner and the housing 112 can then be closed in a simplemanner. The embodiment shown in FIGS. 1 and 2 offers even furtherimproved sealing, with certain difficulty during the assembly on accountof the second bearing 32, which is not split, since first of all thethrottle valve shaft can be inserted into this bearing and only afterthat can the unit of gearing and actuator be inserted into thereceptacles of the bottom housing half 114.

In principle, further embodiments of the throttle valve positioningdevices are conceivable which have the common feature that the throttlevalve circumference lies laterally next to the throttle valve shaft, atleast in the region of the passage location in the throttle valve shaft,in the throttle body. A simple lateral offset of the throttle valve withrespect to the throttle valve shaft without or with only very slightinclination is likewise possible in principle, even though acorresponding adaptation of the inner contour of the throttle body tothe path of movement of the pivotable throttle valve could be necessaryin this respect in order to achieve a good sealing effect. In principle,it is also conceivable to arrange the drive not directly between the twohousing halves but rather at a distance from the throttle valve shaft,so that the two housing halves merely form the throttle body and thebearing arrangement for the throttle valve shaft.

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 17. A throttle valve positioning device including ahousing having a split design and forming a bearing arrangement for athrottle valve shaft, the device comprising: a throttle body; a throttlevalve pivotally arranged within the throttle body; a throttle valveshaft arranged within the body such that the throttle valve sitsthereon, the throttle valve shaft arranged to lead through a shaftpassage into the throttle body and wherein the circumference of thethrottle valve, at least on one side, lies next to the throttle valveshaft at a distance from a passage of the throttle valve shaft in thethrottle body; and wherein the housing, between its halves, furthercomprises an actuator and possibly gearing for positioning the throttlevalve via the valve shaft.
 18. The throttle valve positioning deviceaccording to claim 17, wherein the throttle valve circumference, atleast on the side of the throttle valve shaft passage towards to thedrive side, lies on the vacuum side with respect to the throttle valveshaft.
 19. The throttle valve positioning device according to claim 17,wherein the throttle valve is arranged at an acute angle to the throttlevalve shaft.
 20. The throttle valve positioning device according toclaim 19, wherein the acute angle is between 5° and 25°.
 21. Thethrottle valve positioning device according to claim 19, wherein, thethrottle body, in the region of the adjoining throttle valvecircumference, further comprises a bend whose walls lie perpendicular toa direction of inclination of the throttle valve.
 22. The throttle valveposition, device according to claim 16, further comprising a partingline lying between the housing halves outside the contact region of thethrottle valve circumference on an inside of the throttle body.
 23. Thethrottle valve positioning device according to claim 16, wherein thethrottle valve shaft is mounted in a closed bearing boss on the aide ofthe throttle body opposite the shaft passage toward the drive.
 24. Thethrottle valve positioning device according to claim 23, wherein thebearing arrangement of the throttle valve shaft is effected directly inthe bearing boss of the housing part and wherein the housing comprisesplastic such as thermoset.
 25. The throttle valve positioning deviceaccording to claim 16, wherein the throttle valve further comprises aseating ring arranged at its circumference.
 26. The throttle valvepositioning device according to claim 25, wherein the sealing ring isheld in a circumferential groove in a radially movable manner.
 27. Thethrottle valve positioning device according to claim 25, wherein thesealing ring comprises PEEK with a filling of PTFE or PTFE.
 28. Thethrottle valve positioning device according to claim 16, wherein thethrottle valve comprises a thermoset or a thermoplastic.
 29. Thethrottle valve positioning device according to claim 29, wherein thethrottle valve comprises filled PEI or filled PPS.
 30. The throttlevalve positioning device according to claim 28, wherein the throttlevalve is integrally molded on a sleeve made of metal or plastic andwhich completely or partly encloses the throttle valve shaft and issecured to the latter.
 31. The throttle valve positioning deviceaccording to claim 30, wherein the sleeve of plastic is integrallymolded with the throttle valve on the throttle valve shaft.
 32. Thethrottle valve positioning device according to claim 31, wherein themetallic sleeve is welded to the throttle valve shaft or is welded withthe latter.